The invention relates to a method for joining at least two components, in particular two sheet components of a vehicle body, and a joining element for joining at least two components, in particular two sheet components of a vehicle body.
Such a method and such a joining element can already be gleaned as known from DE 10 2007 058 393 A1. With the method found there for joining at least two components, a rivet sleeve arranged in an aperture of the components, in particular a blind rivet, is deformed by driving a joining mandrel into an opening of the rivet sleeve, at least in sections, in such a way that a form-fit rivet connection of the two components is generated. In order to be able to also generate a high-strength rivet connection, it is provided in the method found there that the joining mandrel inserted into the opening of the rivet sleeve performs a rotation movement causing a relative movement between the joining mandrel and the rivet sleeve.
Such joining methods enable the joining of respective components, even when it is only possible to access one side of only one of the components, wherein the other component is covered. The components joined by means of such a method or such blind rivets are connected to each other in a high-strength manner after the joining process, however, depending on the method, the fixed rivets require a large construction space because they usually have a stable flange that is applied particularly thickly or a placing and closing head by means of which they are applied to at least one of the components. The flange therefore has an increased need for space since it must be stable enough to withstand the reshaping forces.
The object of the present invention is thus to create a method and a joining element of the kind mentioned at the start by means of which respective components can be joined in a high-strength manner with a particularly minimal need for space.
A first aspect of the invention relates to a method for joining at least two components, in particular two sheet components of a car body, by means of a flow-formed rivet sleeve comprising a cladding region, a first edge region and a second edge region, into which flow-formed rivet sleeve a traction shaft comprising a base body and a head can be inserted. Furthermore, the flow-formed rivet sleeve is pushed into respective through openings of the components that at least substantially align with one another, after which the flow-formed rivet sleeve expands in the first edge region as a result of a relative movement of the traction shaft to the flow-formed rivet sleeve and is brought into contact with one of the components.
In order to now be able to join the components in a high-strength manner and in a way that requires particularly minimal space, it is provided according to the invention that the second edge region is bent towards the other component by means of a reshaping tool surrounding the traction shaft, the reshaping tool also being known as a setting tool, and is brought into contact with the other component.
Consequently, in addition to the first edge region, which is expanded in the method, the second edge region of the flow-formed rivet sleeve is thus also plastically deformed and applied to the other component. Unlike what is known from the prior art, the flow-formed rivet sleeve thus does not have a comparatively solid flange or setting and closing head, which is usually dimensioned in such a way that it withstands the reshaping forces during a conventional joining process, but instead, two opposing sides, i.e., the two edge regions of the flow-formed rivet sleeve, are deformed during the method. In this method, a force that deforms the flow-formed rivet sleeve is introduced into the flow-formed rivet sleeve in such a way that the first edge region expands, and the second edge region, which, as previously mentioned, is opposite the first edge region, bends towards the other component. By deforming the two edge regions, it is thus not necessary, in contrast to prior art, for one of the edge regions to withstand the force introduction by the reshaping tool and only the second edge region to be deformed.
By expanding and reshaping the first edge region, a so-called setting head, for example, is formed from the first edge region or the first edge region is reshaped into a so-called setting head. By reshaping the second edge region or the bending thereof towards the other component, a so-called closing head is formed from the second edge region or the second edge region is reshaped into a so-called closing head. The closing head formed by the method according to the invention is arranged opposite the setting head and, like the setting head, is a component of the flow-formed rivet sleeve that constitutes a rivet that is inserted, for example when joining a vehicle body, i.e., when joining sheets of a vehicle roof. The closing head formed by this method has a construction height of a maximum of 1 millimeter, for example, whereas a rivet connection produced according to a conventional method would have rivets having a respective construction height of the setting head of up to 3 millimeters. Furthermore, it is possible by means of the method according to the invention to design the setting head to have a construction height of 2.5 millimeters, for example, while in conventional methods, the closing head would have 8 millimeters. Thus, the space needed for construction of the reshaped flow-formed rivet sleeve can be kept particularly minimal.
By reshaping both the first edge region and the second edge region, construction space is saved, in particular, since the construction height of both the setting head and the closing head can be significantly reduced in comparison to methods already known.
In one advantageous embodiment of the invention, the base body of the traction shaft has at least one form-fit element via which the reshaping tool, by means of which the relative movement of the traction shaft to the flow-formed rivet sleeve is caused, interacts in a form-fit manner with the traction shaft at least when causing the relative movement. As a result, in the method according to the invention, a particularly advantageous transfer of forces, in particular traction forces, can take place from the reshaping tool to the traction shaft, in particular the base body. The reshaping tool is also called the setting tool, since it is used to move the traction shaft relative to the flow-formed rivet sleeve, in particular to move it in a translational manner in order to thus reshape the flow-formed rivet sleeve, in particular to expand the first edge region. This movement of the traction shaft and the reshaping of the flow-formed rivet sleeve, as well as the joining of the components caused by this is also known as setting the flow-formed rivet sleeve. The advantageous transfer of forces, in particular from the reshaping tool to the traction shaft, takes place via the at least one form-fit element of the base body, such that the reshaping tool engages with the base body and thus the traction shaft as a whole in a form-fit manner via the form-fit element of the base body, at least when moving the traction shaft. As a result of this form-fit engagement, traction forces, for example, can be transferred from the reshaping tool to the traction shaft, such that the traction shaft is moved in a translational manner by means of the reshaping tool in such a way that the head of the traction shaft, which, for example, initially protrudes from the flow-formed rivet sleeve, is moved, in particular drawn, at least partially into the flow-formed rivet sleeve, whereby the flow-formed rivet sleeve is reshaped, in particular the first edge region expands.
As a result of the form-fit engagement of the reshaping tool with the traction shaft, particularly high traction forces can also be transferred, such that the flow-formed rivet sleeve can be particularly advantageously reshaped by means of the traction shaft, in particular by means of the head. As a result, the components can be fixedly connected to one another. Furthermore, as a result of the form-fit engagement, unwanted relative movements between the traction shaft and the reshaping tool can be avoided, such that the traction shaft can be moved and positioned in a defined and targeted manner. Thus, a particularly strong connection of the components can be ensured. In particular, it is possible to position the head at least partially in the flow-formed rivet sleeve in a targeted and defined manner, such that the head remains in the flow-formed rivet sleeve, for example after joining the components.
In order to achieve the form-fit engagement, the reshaping tool has, for example, at least one further form-fit element that corresponds to the form-fit element of the base body, the form-fit element engaging with the at least one first form-fit element of the base body in a form-fit manner at least when causing the relative movement between the traction shaft and the flow-formed rivet sleeve.
In order to particularly fixedly connect the components to one another and thus at the same time keep the construction space required particularly low, it is provided in one advantageous embodiment of the invention that the head of the traction shaft has at least one recess which receives material which is displaced during joining. In other words, joining the components results in material displacement. This means that material at least of one of the components and/or material of the flow-formed rivet sleeve is displaced by joining. The displaced material can now flow into the recess of the head. The head, for example, thereby engages with the material which flows into the recess or is displaced in a form-fit manner, such that the head, which remains on the flow-formed rivet sleeve, in particular in the flow-formed rivet sleeve, and on the components after joining, for example, is prevented from detaching. In other words, the danger that the head detaches from the flow-formed rivet sleeve and the components can be kept particularly minimal as a result of displaced material flowing into the recess of the head.
A further embodiment is characterized in that respective diameters, in particular external diameters, of the edge regions are increased during the relative movement. As a result, in particular the construction space required in the axial direction of the flow-formed rivet sleeve or the traction shaft can be kept minimal.
It has been shown to be particularly advantageous when the traction shaft, in its axial direction, comprises a predetermined breaking point between the head and the base body. When joining, the base body is removed from the head in a targeted manner at the predetermined breaking point by the base body pulling off and/breaking off and/or breaking down in a different manner, for example, specifically at the predetermined breaking point. The head of the traction shaft at least partially moved into the flow-formed rivet sleeve by the relative movement between the traction shaft and the flow-formed rivet sleeve and thus at least partially received in the flow-formed rivet sleeve thus remains on the flow-formed rivet sleeve and the components and can be prevented from detaching, for example by means of the material that flowed into the recess. The base body, however, is separated from the head specifically at the predetermined breaking point and thus removed from the head, the flow-formed rivet sleeve and the components, such that the required construction space and the weight of the connection produced can be kept particularly minimal.
The predetermined breaking point is formed, for example, by a local weakening, wherein the traction shaft at the predetermined breaking point, for example, has a smaller thickness, in particular wall thickness, than the regions of the traction shaft connected thereto, wherein these regions connect, for example in the axial direction, to the predetermined breaking point on both sides.
The previously mentioned axial direction of the flow-formed rivet sleeve and the traction shaft coincide, for example, with the direction in which the traction shaft is moved relative to the flow-formed rivet sleeve by means of the reshaping tool.
Finally, it has been shown to be advantageous for achieving a particularly strong connection of the components when the cladding region is formed as a cone or conically and, as a result of the relative movement, is deformed into a cylinder or cylindrically.
A second aspect of the invention relates to a joining element for joining at least two components, in particular two sheet components of a vehicle body. The joining element comprises a flow-formed rivet sleeve, which has a cladding region, a first edge region and a second edge region. Furthermore, the joining element comprises a traction shaft that is inserted into the flow-formed rivet sleeve and thus received at least partially in the flow-formed rivet sleeve and comprises a base body and a head. Here, the flow-formed rivet sleeve can be pushed into respective through openings of the components that at least substantially align with one another, after which the flow-formed rivet sleeve can expand in the first edge region as a result of a relative movement of the traction shaft to the flow-formed rivet sleeve and can be applied to one of the components.
In order to now be able to connect the components to one another in a high-strength manner with minimal required space, it is provided according to the invention that the second edge region can be bent towards the other component by means of a reshaping tool surrounding the traction shaft and can be applied to the other component. Advantageous embodiments of the first aspect of the invention are to be regarded as advantageous embodiments of the second aspect of the invention and vice versa. This means that the joining element according to the invention is designed to carry out the method according to the invention. The flow-formed rivet sleeve and the traction shaft thus form the joining element, which is used for joining or connecting the components in a high-strength and space-saving manner.
In one advantageous embodiment of the invention, the base body of the traction shaft has at least one form-fit element via which the reshaping tool, by means of which the relative movement of the traction shaft to the flow-formed rivet sleeve can be caused, can be brought into form-fit engagement with the traction shall at least when causing the relative movement. As a result, particularly high forces, in particular traction forces, can be transferred from the reshaping tool to the traction shaft.
In order to connect the components to one another in a strong and space-saving manner, it is provided in one advantageous embodiment of the invention that the head of the traction shaft has at least one recess for receiving material which is displaced during joining. This displaced material can be material at least of one of the components and/or material of the flow-formed rivet sleeve, wherein the displaced material can flow into the recess. As a result, it is also possible to prevent detachment of the head that remains, for example, on the flow-formed rivet sleeve and the components, i.e., an unwanted detachment of the head from the flow-formed rivet sleeve and the components, such that the head, which is separated from the base body, for example when joining, remains securely in the flow-formed rivet sleeve.
Here, it has been shown to be particularly advantageous when the recess completely circulates in the peripheral direction of the head. This should be understood to mean that the recess extends completely, i.e., without breaking, in the peripheral direction of the head, such that the recess is formed, for example, to be at least substantially circular or as a closed circle. The recess that is, for example, at least substantially groove-shaped or groove-like can thus receive a particularly large amount of displaced material, such that the head can be secured in a particularly strong manner on the flow-formed rivet sleeve or the components.
In a particularly advantageous embodiment of the invention, the form-fit element is formed as a receiver, in which at least one further corresponding form-fit element of the reshaping tool can be received at least partially. The further form-fit element can be moved, for example, in a support system having the wall regions that at least partially border the receiver of the base body, such that, as a result, the reshaping tool and the base body or the traction shaft as a whole can engage in a form-fit manner. Particularly high traction forces can be transferred as a result. Since in this embodiment, the form-fit element is formed as a receiver and not as a projection, for example, the reshaping tool can be fitted on the base body or pulled over this in a particularly simple manner. Furthermore, it is thus possible to keep the costs, weight and the required space of the joining element low.
To achieve a particularly advantageous form-fit engagement between the reshaping tool and the traction shaft, it is provided in a further embodiment of the invention that the receiver extends completely continuously in the peripheral direction of the base body. This means that the receiver runs completely in the peripheral direction of the base body, i.e., without breaking around the base body, such that the receiver is formed, for example, to be at least substantially circular or as a closed circle. As a result, the reshaping tool, for example, can engage with the base body particularly over a large area, such that even particularly high traction forces can be transferred. Furthermore, the reshaping tool can be placed on the base body in a particular simple, time- and cost-effective manner, such that the components can be connected to one another in a particularly simple manner.
Finally, it has been shown to be advantageous when the traction shaft, in particular in its axial direction, comprises a predetermined breaking point between the head and the base body. When joining, the traction shaft breaks off specifically at the predetermined break point in a controlled manner, such that the base body is separated from the head specifically at the predetermined break point in a controlled manner, in particular pulled off or broken off from the head. As a result, the head can remain on the flow-formed rivet sleeve and the components, wherein the base body can be removed from the head, the flow-formed rivet sleeve and the components and disposed of, for example. The weight and the required construction space of the connection can thereby be kept low. Furthermore, it is possible to avoid an uncontrolled breaking off of the base body from the head by using the predetermined breaking point, such that the head received at least partially in the flow-formed rivet sleeve or the rest of the traction shaft remaining on the flow-formed rivet sleeve does not protrude on the sides of the other component or does not at least excessively protrude from the flow-formed rivet sleeve.
Further advantages, features and details of the invention arise from the description of a preferred exemplary embodiment below, as well as with the aid of the figures.